Nowadays security is a major area of concern. Embedded systems are used in every automotive systems. So, attack from outside network, inside networks, bugs, hacking these are common and major concerns for an automotive security. This paper aims at providing hardware and software solution for security in automotive applications. In this paper we propose a hardware model for encryption as well as a software model that can be used for security, particularly in the Automobile domain. In Automobiles 40 to 50 microcontrollers will communicate over a CAN Bus, this communication can be encrypted, it should allow only authenticate controller to communicate inside as well as outside. In vehicle there are large no of microcontrollers called ECU’s which performs specific action depending on information supplied to them by other ECU’s inside vehicle or the other clusters who are outside vehicle and try to communicate. This will create a wide gateway for misusing the information and manipulations. In this paper, hardware approach is presented for security build on GRP algorithm consisting of structures of Multiplexers can be called as Hardware Security Model(HSM) and in software approach by creating a gateways and only allowing authenticate controllers to communicate .